1. Field of the Invention
This invention concerns a method and apparatus for removing waste selvage formed when weaving on an automatic loom, the removal being implemented by two removing rollers in contact with each other so as to provide a clamping or gripping nip zone between them for drawing a waste selvage away from the woven fabric, with at least one of the removing rollers being directly driven.
2. Discussion of Prior Art
It is known (i..e, U.S. Pat. No. 3,461,920) to bind selvage weft ends into waste warps and thereafter sever the selvage so as to form a main selvage that remains with the fabric and a waste selvage that includes the waste warps and waste wefts. This waste selvage is removed using a removal device and is conveyed to a collecting means, for instance a flanged winding spool or a receptacle. In the prior art device, the removal device comprises two removal rollers defining a gripping nip between them for receiving the waste selvage that is fed to the nip in a tangential manner. One of the removal rollers includes longitudinal flutes at its surface and is fitted with a drive powered by the loom breast beam. This removal roller cooperates with a second removal roller fitted with a resilient covering. The waste selvage is forced into the longitudinal flutes to achieve thereby a sort of mechanically positive locking between the waste selvage and the flutes. Such removal devices, wherein the removal force is generated exclusively at the gripping nip between the removal rollers, has a disadvantage in that the waste selvage may tear or lose tension, in particular when said waste selvage is irregular, i.e., non-uniform. As a result, the auxiliary warps no longer form an open shed in an orderly manner, resulting in an improper insertion of the wefts until it is necessary to shut down the loom to remedy the defect.
Such prior art devices furthermore also have the disadvantage that waste selvage often wraps around one of the removal rollers and results in damage to the removal device. To avoid such a problem, it is known from German O.S. 26 20 894 to make the removal rollers hollow and to perforate them for enabling expelling of compressed air through the perforations.
It is furthermore known from U.S. Pat. No. 4,616,680 to fit removal rollers with a smooth surface forming a clamping or gripping zone between them for engaging the waste selvage. In such design, the waste selvage is fed to the surface of one of the removal rollers before it reaches the gripping nip, but this roller is not driven directly. Because an idler roller in the system together with the driven roller defines the gripping nip, the first roller is frictionally driven by the waste selvage. Thereupon, the waste selvage runs over the driven roller over a wrap angle of approximately 90.degree. towards a collection device. In such design, the removal force is introduced into the waste selvage substantially only at the gripping nip between the removal rollers.